A lot of cleanup to make the site smoother, IE8 fixes, removing dead code,...

A lot of cleanup to make the site smoother, IE8 fixes, removing dead code, make the arrow transition smoother.

* On the main page, update card with new design.
* Simplify a lot of styles and layout.
* Clean up the "about page"
* Using css transitions for the arrow slide.
* Change all BrowserID text to Persona.
* Fix a problem on the main site where the footer would was not at the bottom in Webkit and Opera browsers.
* Fix the background color or IE8 in the signUpForm and congrats messages.
* When signing in to the main site, use a tooltip instead of error message on incorrect password.